                            :subcat {:3 {:sem {:obj subject-semantics}}}}}))
         
         sentential-adverb it-pos/sentential-adverb
+        subj-obj-humanness
+        (let [human (atom :top)]
+          {:synsem {:sem {:subj {:human human}
+                          :obj {:human human}}}})
         transitive it-pos/transitive
         verb-aux it-pos/verb-aux
         verb-subjective it-pos/verb-subjective]

                                      :2 '()}}}}}

      ;; essere: prepositional phrase
      (let [obj (atom {:pred :top
                       :place true})
            pred (atom :top)]
        {:unify [essere-common]
         :notes "essere-prepositional-phrase"
         :synsem {:cat :verb
                  :aux false
                  :sem {:pred pred
                        :obj obj}
                  ;; TODO: should not need agreement: should be covered by
                  ;; essere-common.
                  :subcat {:1 {:cat :noun}
                           :2 {:cat :prep
                               :subcat '()
                               :sem {:pred pred
                                     :obj obj}}
                           :3 '()}}})
         
      ;; TODO: do we need this? maybe remove?
      {:unify [essere-common]

       :synsem {:sem {:pred :be}}}

      ;; essere: copula ;; note that we don't enforce agreement the same here as we do in essere-adjective: TODO: try to make more consistent.
      {:unify [transitive essere-common gender-and-number-agreement-1 subj-obj-humanness]
       :notes "copula" ;; significant only for debugging.
       :synsem {:cat :verb
                :subcat {:1 {:cat :noun}
                         :2 {:cat :noun
                             :pronoun {:not true} ;; accusative pronouns cause unbounded depth-first searches on the subject side. (TODO: not sure if this problem is still present)
                             :def {:not :demonstrativo}}}
                :sem {:pred :be
                      :activity false
                      :discrete false}}}

      ;; essere: intensifier
      ;; this is for e.g "essere più alto di quelle donne belle (to be taller than those beautiful women)"
